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New Member

To BVI or not to BVI????

Okay I am a novice when it comes to setting up bridging but I have been asked to help a friend who has his own mini ISP to create something that will work for him.

Here is the network layout.

there are 2 bridge-groups

BG1 contains 4 members

ATM1/0.364 Location1 (same as below)

ATM1/0.365 Location2

ATM1/0.366 Location3

ATM1/0.367 Location4

BG2 contains 2 members

ATM1/0.369 Location1 (same as above)

ATM1/0.370 Location5

Also there are 2 additional connections through this same router to the internet

ATM1/0.368 Location1 to the internet

ATM1/0.371 Location5 to the internet

Yes that means that Location1 has 3 connections to this router

1 for BG1

1 for BG2

1 for internet


Location5 has 2 connections.

1 for BG2

1 for internet

Currently bridging is setup as irb using the default ieee, but there are no BVIs implemented. As I understand it, if there are no BVIs in place then all traffic is bridged within a Bridge-group.

This is how we would like it to work, what we are seeing is that the traffic between bridge members is showing bad packet loss.

I was asked to maybe setup a BVI for each bridge-group and set IP routing to enabled for each BVI. But I am hesitant because I am not sure how this will affect the dedicated internet connections for "Location1" and "Location5" .

Any help or advice will be greatly appreciated.



Hall of Fame Super Gold

Re: To BVI or not to BVI????

Hi Tomas,

Yes you can make additional BVI to do routing, possibily one per PVC, however you have to consider customer addreses at the different locations is addressing network. Right now things are bridged around and is not very clear how these work, possibly they are using the same subnet everywhere, or they are doing NAT with the adsl modems/ router ?

Once you find out how to deal with address, you can configure one BVI per PVC, that will allow you to route between PVCs. All that should not affect internet in loc 1 and 5, because customer probably has set routing so that private network goes to another line, however you may want to get more details on that.

New Member

Re: To BVI or not to BVI????

Thanks for your quick response. I will try to get the address info on the different network segments and see where to go from there

Hall of Fame Super Gold

Re: To BVI or not to BVI????

While you are at it, check which adsl/modem router they are using, if it supports routed encapsulation instead of bridged, things get even easier as you wouldn't need the BVI at all.

The problem you may have is that once you get into the details of customer's address, you may have to configure some routing to support them. With bridging, it would never be your problem.

This could interfere with other addresses, etc that your router is also supporting. If necessary, that can be solved using VRF that makes so that you configure a virtual router for certain interfaces only while other are excluded.

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